Wireless networks for both business and home use are rapidly becoming popular. Wireless networks provide convenient networking and Internet access by eliminating the need for wired connections between computers and other network devices, e.g., routers, printers, storage devices, etc.
Wireless networks are especially convenient for users of portable wireless stations, such as laptop computers, notebook computers, personal digital assistants (PDAs), and the like. Such wireless stations can easily be transported between hotspots (locations where wireless networking/Internet access is provided). New hotspots are appearing frequently at such locations as airports, malls, coffee shops, restaurants, and hotels.
The 802.11 family of standards (WiFi) provides examples of conventional wireless networks. The 802.11 family of standards is expanding to provide enhanced features, such as more channels, better security, and greater bandwidth. An increasing variety of wireless station types based on 802.11 technologies are being developed. Many of these devices are personal computing devices. However, other types of devices, such as cameras and music recorders, are also being developed.
The connection of a wireless station to a wireless network is facilitated by an access point (AP). APs contain radio transceivers that provide wireless communication to wireless stations and also contain network interfaces, such as Ethernet ports, that provide communication to an upstream network. An AP may optionally comprise a router and/or switch, to facilitate communication among computers on the network. For example, an AP may contain an Ethernet port that facilitates connection thereof to the Internet, such as via a cable modem or a digital subscriber line (DSL) modem, and may also contain a plurality of switched ports that each facilitates communication with one or more local area network (LAN) computers.
Current 802.11 implementations require the wireless station to initiate the association with the AP. A wireless station can passively discover some information regarding available wireless networks via information elements provided in the beacon that is broadcast from each AP. If a wireless station detects more than one AP (such as when multiple beacon signals are detected), a single AP must be selected for connection. However, while some characteristics of the wireless network can be determined before the wireless station associates with the AP, many other characteristics cannot be determined until after association. In particular, the beacon signal does not currently provide any information regarding the upstream network to which the AP is connected. For example, the wireless station can determine from the beacon signal the channel number, signal strength, and SSID of the AP. However, the wireless station cannot determine whether or not the AP has an Internet connection or whether DHCP (Dynamic Host Configuration Protocol) support is available.
Some wireless stations have been provided with some form of utility to facilitate the AP selection process. For example, a utility may provide a dynamic table listing all detected APs and displaying all of the information regarding each AP that can be determined from the APs' beacons. Based on this information, the user can manually select one of the detected APs for association.
Alternatively, some utilities allow users to create one or more profiles in order to save previously associated AP information for future connections. For example, the Windows XP operating system includes a configuration utility referred to as Windows Zero Configuration. Using the Zero Configuration setup screens, a user can define multiple wireless configurations and can define a prioritization of those configurations. When searching for available wireless networks, the configuration utility will attempt to connect to any wireless networks that match the predefined configurations. These types of profiling mechanisms are limited in that they only consider the limited information about the wireless network that can be obtained from the beacon signals, without consideration of the characteristics of the upstream network. In addition, these mechanisms merely select the first AP which satisfies the requirements defined by the profile, without regard for the relative advantages provided by the other APs.
The problem of selecting an AP with which to initially associate is especially troublesome for mobile devices. These mobile devices are capable of roaming during operation and therefore may require handover from a first AP to a second AP without interruption of coverage. Handover to an AP that does not provide the necessary network services can cause a noticeable disruption in service as the mobile device attempts to associate with another AP. In the case of WiFi telephone handsets, this disruption may result in a dropped call.
Accordingly, there is a need for an improved method to enable a wireless station to select an access point from a plurality of access points for association.